1. Field of the Invention
The present invention relates generally to optical recording systems, and more specifically to positioning light beams within optical recording systems.
2. Description of the Related Art
Many data recording systems employ a means of reading the recorded data immediately after it is written onto the storage media so that the accuracy of the recorded data can be quickly ascertained. For example, in linear magnetic tape systems the read-write head array is duplicated within a single structure to enable immediate verification of the written data accuracy with the tape moving in either direction. In optical disc systems the verification function is usually implemented by reading the written data on a consecutive turn of the disc. Read-after-write (RAW) is a necessary function for any high fidelity data recorder and its implementation is therefore required in a linear optical tape recording system.
In a typical high data rate optical tape recording system the RAW function is complicated by simultaneous multi-track recording using multiple write beams, necessitating implementing multi-track RAW. For example, in a 64-beam recorder using a skewed 8xc3x978 array of modulated optical beams, the RAW function requires a like array of 64 continuous beams to read the data. This beam array must position a read beam immediately down track of each write beam, for both directions of tape travel. Each of the read beams in the read array must be located exactly on the data bit-track written by the write beam array, and at a given distance down track. The entire read beam array must therefore be adjusted in both the down track and cross track directions. Although these two adjustments can be implemented by a two axis actuator, it is greatly beneficial if both adjustments can be obtained from a single axis actuator. It is also desirable to have the RAW function implemented by a physical device that is relatively insensitive to small mounting position errors and dynamic vibrations.
The present invention provides a rotatable wedge disposed relative to a reflective member oriented to reflect a light barn such that a the reflected light beam, upon passing through the rotatable wedge, is directed to a position on a recording medium according to a position of the rotatable wedge. The rotatable wedge is rotatable between at least a first position and a second position. In one embodiment of the present invention, the rotatable wedge is rotatable about an axis that is substantially orthogonal to the reflective member. In another embodiment the rotatable wedge is translatable in a direction substantially parallel to the reflective member.
Additional features, aspects and benefits of various embodiments of the present invention will become apparent upon review of the following description.